#define _CRT_SECURE_NO_WARNINGS 1
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <assert.h>

class Stack {
public:
	void Init();
	void Push(int x);
	void Pop();
	//...
private:
	int* _a;
	int _top;
	int _capacity;
};